OSPF Design: Understanding OSPF Areas

Questions and Answers

To limit Link State Advertisement propagation to specific areas

Backbone Router

Area Border Router

4.2 billion Signup and view all the answers

Hub-and-spoke topology Signup and view all the answers

Autonomous System Border Router Signup and view all the answers

Reducing unnecessary updates and enabling routers to maintain separate link state databases Signup and view all the answers

Internal Router Signup and view all the answers

Area Border Router Signup and view all the answers

To enable communication between areas Signup and view all the answers

Study Notes

OSPF areas are crucial to understanding OSPF design, and OSPF areas are divided into two types: Area 0 (backbone) and other areas (1-4.2 billion).
OSPF areas are introduced to limit LSA (Link State Advertisement) propagation to specific areas, reducing the need for every router to update its network map.

OSPF areas allow routers to maintain a separate link state database for each area, reducing unnecessary updates.
Areas prevent routers from having to recalculate their network maps every time a change occurs in the network.

OSPF areas create a two-tier hierarchy, with Area 0 (backbone) at the top and other areas (1-4.2 billion) below.
Communication between areas must traverse through Area 0, ensuring a loop-free area topology.
This design creates a hub-and-spoke topology, with Area 0 as the hub and each area as a spoke.

Internal Routers: Routers with all interfaces in a single area.
Backbone Routers: Routers with at least one interface in Area 0.
Area Border Routers (ABRs): Routers with one or more interfaces in Area 0 and one or more interfaces in another area.
Autonomous System Border Routers (ASBRs): Routers that perform redistribution from a foreign routing protocol into OSPF.

Internal Routers: Routers 1, 2, 5, 6, and 7 are internal routers in this topology.
Backbone Routers: Routers 1, 2, 3, and 4 are backbone routers.
Area Border Routers: Routers 3 and 4 are ABRs, maintaining separate link state databases for each area.
Autonomous System Border Routers: Router 7 becomes an ASBR when redistributing routes from a foreign routing protocol into OSPF.

OSPF areas are divided into two types: Area 0 (backbone) and other areas (1-4.2 billion).
OSPF areas limit LSA (Link State Advertisement) propagation to specific areas, reducing the need for every router to update its network map.

OSPF areas allow routers to maintain a separate link state database for each area, reducing unnecessary updates.
Areas prevent routers from having to recalculate their network maps every time a change occurs in the network.

OSPF areas create a two-tier hierarchy, with Area 0 (backbone) at the top and other areas below.
Communication between areas must traverse through Area 0, ensuring a loop-free area topology.
This design creates a hub-and-spoke topology, with Area 0 as the hub and each area as a spoke.

Internal Routers: have all interfaces in a single area.
Backbone Routers: have at least one interface in Area 0.
Area Border Routers (ABRs): have one or more interfaces in Area 0 and one or more interfaces in another area.
Autonomous System Border Routers (ASBRs): perform redistribution from a foreign routing protocol into OSPF.

Internal Routers: have all interfaces in a single area and do not connect to other areas.
Backbone Routers: connect to Area 0 and enable communication between areas.
Area Border Routers: maintain separate link state databases for each area and connect multiple areas.
Autonomous System Border Routers: connect OSPF to other routing protocols and enable route redistribution.